32 ANNUAL OF SCIENTIFIC DISCOVEKY. 



three times that of the famous Menai Bridge. This is to be ap- 

 proached, on either side, by a succession of arches, the whole 

 length being more than 1 miles, and the total estimated expense 

 6,000,000 dollars. The cables will be four in number, each 14 

 inches in diameter, of No. 9 wire, arranged one at each outer 

 side of the platform, and two near the centre, the whole width 

 of the platform being 80 feet. The platform will have six wrought- 

 iron trusses, each 10 feet deep, for its whole length. There will 

 be a, footway along the centre, 10 feet wide, a horse-railroad on 

 each side, each 16 feet wide, and a roadway on each outside of 

 the platform, also 16 feet wide, with a projection of the cross- 

 beams of 3 feet on each side, to receive the connections from 

 the outer cables. The towers will be of granite, 350 feet high, 

 and 150 feet by 90 feet at their base. Asa whole, no work of the 

 same character yet executed approaches this in magnitude. 

 Engineering, July, 1867. 



A full description of the bridge by Mr. Roebling, may be found 

 in the "Journal of the Franklin Institute," Philadelphia, for Oct. 

 and Nov., 1867. 



GREAT BRIDGES. 



Bridge oner Straits of Messina. The width of the Straits which 

 secures the least depth of water for the foundations of the 

 (bridge) piers is 13,123 feet from shore to shore; the depth of the 

 piers on this line would be 360 feet below the water level, while 

 on a shorter line the depth is 70 feet greater. The height under 

 the spans of the suspension bridge proposed by M. Oudry would 

 be 164 feet, making the total height from foundation to flooring 

 524 feet; the length of the spans would be 1,000 metres or 3,281 

 feet each. 



Bridge over the Mississippi at St. Louis. This will accommo- 

 date two double tracks of rails for street-cars, beside sidewalks for 

 foot-passengers, and will consist of three arches, the central arch 

 having a span of 515 feet, and the two side arches 497 feet. One 

 pier will be nearly 200 feet in height from the bed of the river and 

 110 feet in width, and the other 170 feet in height. 



New Suspension Bridge at Niagara Falls. Towers to be 105 

 feet high, span 1,250 feet, height above water 175 feet, and width 

 of roadway 10 feet. Intended for carriages and pedestrians. 



SUEZ CANAL. 



Though the distance from the Red Sea to the Mediterranean is 

 only about 70 miles, it is one of the most difficult engineering 

 undertakings of modern times. After cutting this canal about 

 20 miles of the line to the requisite width, an obstacle, thought 

 by many to be insurmountable, has been met with. It passes 

 through a shallow lake for a considerable distance, and it is in 

 this that the trouble has developed. The bottom is a quag'mire, 

 and, as fast as it is thrown out, fills up again, by oozing in from the 

 bottom and sides. A difficulty under which the railroad company 

 labor has also been found to threaten the canal-builders even 



